What units does the rotation argument expect when creating objects?
It is using radians. 1 radian = 57.2957795 degrees. Without the need to import another module you can use a degree value with (3.14159 * degrees / 180) or just quickly import pi from math if you don't want to define it or you could alternatively use round(math.radians(degrees)).

import bpy
from math import pi

bpy.ops.object.lamp_add(type='AREA', ... ,  rotation=(0, (pi * degrees / 180), 0))